Tyk's health check always returns 200

[vanny96]

Version and Environment

• Branch/Version: Master
• Environment: All

Describe the bug
As already reported in the past at #2248, the health check currently always reports 200 even if the actual state is either warn or fail. This causes issues as the pod would try to accept requests but fail as it isn't fully working.

On a on premise setup, we noticed that some of the pods spinning up failed the initial fetching from the control plane. Instead of being restarted, they started accepting requests which raised the number of 404 errors. A functioning health check would have avoided this.

Reproduction steps
Steps to reproduce the behavior:

1. Remove redis/Setup RPC with wrong configurations

Actual behavior
The container is still healthy and receiving requests

Expected behavior
The container should be unhealthy and restart until healthy (if ever)